Tackling Johne's disease through a healthy livestock iniaitive
JOHNE’S disease is estimated to cost the UK cattle industry £13 million a year, but a project in south west England is helping farmers to tackle this hidden problem.
When Steve Jones took over as farm manager at Cannington College’s Rodway Farm in Somerset, the unit was in desperate need of investment.
Six years on it has enjoyed a massive revival, both in terms of dairy productivity and student numbers. But in 2012 the staff discovered one more challenge to overcome, following the diagnosis of 10 cows with Johne’s disease.
Fortunately, Mr Jones discovered the disease before it had spread too far, having taken part in the Healthy Livestock project, run by Duchy College.
Offering up to 70 per cent funding for veterinary tests and health planning, the EU-funded project is tackling some of the commonest animal health problems in the South West.
In March, the farm’s vet David Taylor from FarmVets SouthWest tested 30 cows for Johne’s using milk records, and found six of them were infected with the disease. Although herdsmen Stewart Bell and George Stickley had selected a couple of cows which they thought might be at risk, the others were totally unexpected. Mr Bell says: “You can see which cows’ coats are dull and when body condition is poor, but four of the six seemed perfectly fine – it was quite a shock.”
According to Mr Taylor, between 80 per cent and 90 per cent of the herds the practice has tested have been Johne’s positive. In a follow-up whole herd test at Cannington, he found another four infected cows, two of which have since been culled. “We haven’t tested the dry cows – we will do them in three months’ time, so then the whole herd will be covered.”
In the past, the college had culled quite a lot of cows for mastitis, high cell counts and poor feet, without realising all could be signs of Johne’s. “We’ve been lucky the incidence is quite low – we should be clear in three or four years,” says Mr Jones. “If we ignored it, it would quickly become a much bigger issue.”
In a bid to address the disease, he is paying closer attention to calf management, taking the calves away from the pen as soon as possible after birth and ensuring they all receive at least four litres of high quality colostrum in the first hour of life. “Half of all calves don’t get enough colostrum if suckling from the udder,” says Mr Taylor. “Those which do get enough have fewer scouring problems and better growth rates – and if they’re content and full they will lie down and not be sucking at dirty udders or straw.”
The farm workers keep colostrum from the best cows and freeze it, ready for use as each calf is born. As part of the veterinary practices ‘heifer performance programme’, they record the calf’s details, weigh it and blood test it to check its antibody levels are high in reaction to the beneficial colostrum.
“We’ve got a separate calving area for any cows which have tested positive to Johne’s, and will cull them at the end of their next lactation,” says Mr Taylor. “If we have any inconclusive results we will put those cows to a beef bull so as not to risk spreading the disease to a heifer replacement.”
The farm does not buy in any cattle, but should it become necessary it would be essential to buy from a known health-status herd, he adds. “If you haven’t got enough replacements you need to look at whether there’s an underlying problem which needs to be addressed. If you do buy anything in, test it regularly to make sure it stays clear.”
Mr Jones has paid close attention to improving cow fertility this year, after culling 35 of the 230-strong herd for poor fertility last year. “We had a calving index of 398 days, which isn’t bad, but we were achieving it by culling anything we couldn’t get back in-calf – and that loss is just too high.”
The cows calve year-round, with a lot of heifers being inseminated with sexed semen, with the best cows inseminated with dairy, rather than beef semen. “We’ve changed our feeding a lot – I think the cows were getting too fat towards the end of their lactation, which was giving us fertility and foot problems,” says Mr Jones.
Maiden heifers are housed for 60 days before they calve, with dry matter intakes monitored. “If intakes fall below 12.5kg a day we know something is wrong.” Cows have a 42-day dry period, during which they are housed to reduce stress and changes to their diet.
After calving in straw pens, they are moved to the neighbouring hospital pen for two days before joining the main milking group. “We try to move them in groups of three or four to minimise stress,” says Mr Jones. “And we weigh them every day between calving and getting pregnant again. Before we changed the rations, they were getting 12kg of concentrates and 9kg in the total mixed ration, which was too much – now they’re getting 6kg in the parlour and 7kg out of it, and it’s made a big difference.”
The pregnancy rate has improved to 27 per cent, significantly above the national average of 15 per cent. And with the youngstock now receiving such close attention, Mr Jones hopes to grow the herd quickly. “If the calves are healthier they should grow quicker, reach their first service faster, and produce more milk throughout their lifetime. At the moment we’re calving heifers at 25.7 months old, and we want to bring that down to 24 months.”
The herd is averaging over 10,000 litres per cow, and this winter Mr Jones has split the milking group into high and low yielders, to reduce feed costs. “The low yielders get a bit less concentrates, which is reducing our costs without impacting on yield.”
Other changes in the pipeline include a new cubicle shed with two robot milkers, which will enable the herd to grow to 400 over the next two years. “We put in a new parlour three and half years ago, and new sheds two and a half years ago, with automatic feeding, automatic footbaths, scales and so-on,” says Mr Jones. “Over the past six years we’ve grown from about 40 agriculture students to almost 200 – we need to have cutting edge technology, but designed in an easy way to handle, and now we’re well on the way to getting that.”
Johne’s disease (mycobacterium avium paratuberculosis) is a degenerative disease in cattle which causes production losses, scouring, wasting and eventually death. It is most common in cattle aged two to six years old, and is transmitted via faeces, milk and colostrum, usually to young calves. The disease often goes relatively unnoticed, as clinical cases only make up 5-10 per cent of the infection load. However, sub-clinically infected animals are a significant source of disease transmission. Johne’s can be an underlying cause of many other conditions such as lameness and poor fertility, so cows are often culled for other reasons before reaching the clinical stage of the disease.
- Infected cows give 1-4 litres less milk per day, depending on stage of infection
- Test positive cows give 212 litres less milk per 305-day lactation
- Loss of milk alone equates to £27 per cow annually
- Higher culling rates
- Increased incidence of other disease, due to suppression of the immune system, and failure to respond to treatments for those problems